class Circle {
    private double radius;
    public Circle() {
    }

    public void setRadius(double r) {
        radius = r;
    }

    public double getRadius() {
        return radius;
    }

    public double calculateArea() {
        return Math.PI * radius * radius;
    }

    public double calculateCircumference() {
        return 2 * Math.PI * radius;
    }

    public static void main(String[] args) {
        Circle circle = new Circle();

        circle.setRadius(12.0);

        double area = circle.calculateArea();
        System.out.println("面积: " + area);
        
        double circumference = circle.calculateCircumference();
        System.out.println("周长: " + circumference);
    }
}